physiology exam 2 Flashcards

1
Q

sensory system

A

part of NS consisting of sensory receptors that receive stimuli, neural pathways to conduct info, and brain to process info

may or may not lead to lead to conscious awareness of stimuli
(DONT notice BP changes)

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2
Q

sensation

A

stimulus info reaches consciousness

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3
Q

perception

A

awareness of sensation

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4
Q

sensation ex

A

feel pain

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5
Q

sensory processing

A

Transduction of stimulus energy into graded potentials and then APs in afferent neurons
Pattern of APs is a code that provides info about stimulus such as location, intensity and input type
Communicate with the brain to process info
May determine reflexive efferent responses, perception, memory storage, assignment of emotional significance

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6
Q

sensory receptors

A

at peripheral ends of afferent neurons change this info into graded potentials that can initiate APs to travel to CNS

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7
Q

adequate stimulus

A

type of stimulus which a particular receptor responds in normal functioning

a receptor may respond at low threshold to other stimuli

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7
Q

receptor

A

2 kinds
1. sensory receptor at peripheral end of afferent neurons trigger graded potentials to initiate APs
2. plasma membrane proteins that binds chemical messengers and trigger signal

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8
Q

mechanoreceptors

A

respond to mechanical stimulus like pressure or stretch
- resp. for touch and muscle tension
stimuli alter the permeability of ion channels on receptor membrane, changing membrane potential Vm

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9
Q

thermoreceptors

A

detect cold warmth sensations

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10
Q

photoreceptors

A

respond to wave length

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11
Q

chemoreceptors

A

respond to binding of chemicals to membrane
smell and taste

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12
Q

nociceptors

A

sense pain due to tissue damage
can be activated by variety of stimuli (heat, chemical, mechanical)

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13
Q

sensory transduction

A

process a stimuli is transformed into electrical response
Regardless of OG form the signal that activates sensory receptors, the info must be translated into graded potentials or APs
- involves open/closing of ion channels
- gating of channels allows a change in ion flux across receptor membrane and produces graded potential called receptor potential

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14
Q

afferent neuron receptor potential for sensory transduction

A

receptor membrane region where initial ion channel changes does NOT generate APs
- local current flows a short distance. along axon to voltage gated ion channels and can generate APs
- usually 1st node of ranvier if myelinated

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15
Q

receptor potential

A

like graded potentials, response to intensities and diminishes as it travels

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16
Q

receptor potential when receptor membrane is on a separate cell

A

receptor potential releases NT
- NT diffuses across cleft ~ receptor/afferent neuron and binds receptor protein on afferent neuron
- junction is a synapse
- NT binds binding site generates graded potential in afferent neuron
- analogous to EPSP (or IPSP)

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17
Q

true of all graded potentials

A

magnitude of receptor potential or graded potential decreases with dist. from origin

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18
Q

graded to AP

A

if intensity of depolarization at 1st excitable node of ranvier in afferent neuron is large enough to bring membrane to threshold, APs are generated and propagate along afferent
as long as receptor potential keeps afferent neuron depolarized to level at/above threshold, APs fire and propagate

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19
Q

magnitude of receptor potential

A

determines frequency of APs,
does NOT determine amplitude of APs

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20
Q

factor control magnitude of receptor potential

A

stimulus strength, rate of change of stimulus strength, temporal summation of successive receptor potentials and
adaptation

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21
Q

adaptation

A

decrease in receptor sensitivity which results in decrease in AP freq. in afferent neuron despite continuous presence of stimulus

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22
Q

slowly adapting receptors

A

tonic
maintain persistent or slowly decaying receptor potential during a constant stimulus
initiating APs in afferent neurons for duration of stimulus

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23
Q

tonic receptors

A

slowly adapting receptors
maintain persistent or slowly decaying receptor potential during a constant stimulus
initiating APs in afferent neurons for duration of stimulus

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24
Q

rapidly adapting receptors

A

phasic receptors
generate receptor potential and APs at onset of stimulus but quickly cease responding
adaptation may be so quick that only 1 AP is generated
some receptors may only initiate APs at onset of stimulus or w/ burst at beginning of stimulus

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25
Q

phasic receptors

A

rapidly adapting receptors
generate receptor potential and APs at onset of stimulus but quickly cease responding
adaptation may be so quick that only 1 AP is generated

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26
Q

coding

A

conversion of stimulus energy into signal that conveys relevant sensory info to CNS
- begins at receptive neurons in PNS
relevant info:
- type of input
- intensity
-location of body

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27
Q

sensory unit

A

single afferent neurons with receptor endings
- the peripheral end of an afferent neuron has many branches, each with a receptor

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28
Q

receptive field

A

area of body that leads to activity in particular afferent neuron when stimulated
usually overlap other afferent neurons receptive fields so multiple sensory units activate

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29
Q

stimulus type

A

modality - temp, sound, pressure, taste
given receptors are particularly sensitive to 1 modality bc of single transduction mechs and ion channels in membrane

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30
Q

modality

A

stimulus type - temp, sound, pressure

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31
Q

receptive fields overlap

A

a single stimulus can simultaneously give rise to sensations of different modalities
EX: ice = touch and cold

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32
Q

stimulus intensity

A

APs all same amplitude
FREQ. of APs
increased stimulus strength = larger receptor potential = more frequent APs
as stimulus strength increases, adj. receptors are activated = summation of local currents
stronger stimuli affect larger area and can activate other afferent neurons

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33
Q

recruitment

A

activating receptors on additional adj. afferent neurons given strong stimulus

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34
Q

stimulus location

A

coded by site of stimulated receptor
APs from each receptor travel unique pathways to specific regions of CNS assoc. w/ specific modalities and locations = labeled lines

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35
Q

labeled lines

A

APs from each stimulated receptor travel unique pathways to specific regions of CNS assoc. w/ specific modalities and locations

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36
Q

acuity

A

precision of locate/discerning stimuli from adj. one depends on convergence of neural input
greater convergence = less acuity
factors affecting acuity:
1. size of receptive field
2. density of sensory units
3. amount of overlap in nearby receptive fields
neuron w/ small receptive field can be located most precisely but receptive field overlap can help with localization of stimuli

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37
Q

acuity example

A

2 pt discrimination
easy to distinguish stimuli applied to skin on lips were sensory units are small and numerous
hard on back w/ few sensory units that are large and spaced

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38
Q

importance of receptive field overlap

A

afferent neurons respond most vigorously to stimuli applied directly at center of its receptive field bc there is greatest receptor density
decreased response at periphery
firing freq. of afferent neuron related to stimuli strength
receptor endings of different afferent neurons overlap, a stimulus will trigger activity in 1+ sensory unit.

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39
Q

high freq. EX

A

moderately intense stimulus was applied at center of receptive field OR
strong stimulus was applied at periphery
Therefore, neither intensity nor the location of stimulus can be detected w/ single afferent neuron.

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40
Q

lateral inhibition

A

enables localization of stimulus site
info from receptors at edge of stimulus is INHIBITED compared to info from afferent neurons at the center
afferent neurons in center have higher firing freq.
- reduces # of APs

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41
Q

lateral inhibition EX

A

press in a pencil on skin
- can localize point precisely
lateral inhibition removes info from peripheral regions

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42
Q

lateral inhibition importance

A

in retina for visual acuity

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43
Q

central control of afferent info

A

all signals subject to mods at synapses along pathways before reaching CNS
lateral inhibition reduces incoming info
RETICULAR FORMATION & CEREBRAL CORTEX control input of afferent info via descending pathways
inhibitory control by synapses or via interneurons that affect other neurons in pathway

44
Q

afferent sensory pathways

A

formed by chains of 3+ neurons connected by synapses
chains travel in bundles carrying info into CNS
called ASCENDING PATHWAYS up to brain

45
Q

central processes of afferent neurons

A

synapse on interneurons
diverge or converge on second order neurons and so on til info coded in APs reaches cerebral cortex

46
Q

second order neurons

A

interneurons upon which afferent neurons synapse
go on to synapse on 3rd order… up to cerebral cortex
(coded in APs)

47
Q

ending of ascending pathways

A

pass brainstem and thalamus to cerebral cortex
- cross to side of CNS opposite the location of sensory receptors

48
Q

somatic receptors

A

carry info from skin/bone/tendons, etc to somatosensory cortex in parietal love posterior to central sulcus

49
Q

central sulcus

A

separates pariental and frontal loves

50
Q

somatosensory cortex

A

parietal lobe, posterior to central sulcus

51
Q

visual cortex

A

occipital lobe

52
Q

auditory cortex

A

temporal lobe

53
Q

gustatory cortex

A

tastebuds, adj. to somatosensory cortex in parietal lobe

54
Q

olfactory cortex

A

under frontal/temporal loves

55
Q

end point of processing afferent info

A

cerebral cortex
integration

55
Q

Golgi tendon organs

A

monitor muscle tension
tendons connect muscle to bone

56
Q

nonspecific ascending pathways

A

activated by diff. types of sensory units
nonspecific neuron is polymodal neuron
end points: brainstem reticular formation and thalamus –> cerebral cortex

57
Q

cortical association areas

A

adj. areas to primary sensory area
process info further
from primary sensory areas

58
Q

factors affecting perception

A
  1. sensory receptor mechs (adaptation)
  2. emotions, personality, experience
  3. not all sensory info gives rise to conscious sensation - much info is canceled out
  4. we lack suitable receptors for many types of stimuli
  5. damaged neural networks may give faulty perceptions - phantom limb
  6. drugs
  7. mental illness - hallucinations
59
Q

cortical assoc. area

A

region of cerebral cortex where info from primary sensory cortical areas is relayed for further processing

60
Q

somatic sensation

A

Sensation from the skin, skeletal muscles, bones, tendons, and joints is initiated by specific somatic receptors

61
Q

touch and pressure

A

mechanoreceptors stimulation
linked to networks of collagen fibers within fluid filled capsule
networks transmit mechanical tension to ion channels in neuron endings, activate them
slowly adapting receptors = pressure sensation
rapidly adapting = touch, move, vibrations

62
Q

Merkel’s corpuscle

A

lowly adapting mechanoreceptor, touch and pressure

63
Q

Pacinian corpuscles

A

rapidly adapting mechanoreceptor, vibration and deep pressure

64
Q

Ruffini corpuscle

A

slowly adapting mechanoreceptor, skin stretch

65
Q

posture and movement

A

muscle spindle stretch receptors and Golgi tendon organs
mechanoreceptors in muscle and tendon
Golgi tendon organs monitor muscle tension
also, Vision and the vestibular organs
kinesthesia = sense of movement at joint.

66
Q

muscle spindle stretch receptors and Golgi tendon organs

A

mechanoreceptors for posture and movement
Golgi tendon organs monitor muscle tension

67
Q

temperature

A

info transmitted along small diameter afferent neurons with little/no myelination
thermoreceptor neurons originate as free neuron endings
temp sensors are ion channels in plasma membrane of axon terminals belonging to TRP transient receptor potential proteins
isoforms of TRP channels have gates that open for diff temps
when active/open, allow nonspecific flux of cations dominated by depolarizing inward flux of Na and Ca2+

68
Q

transient receptor potential proteins

A

channels; actual temperature sensors are ion channels in the plasma membranes of the axon terminals
Different isoforms of TRP channels have gates that open in differ- ent temperature ranges
activate/open allows nonspecific inward flux of cations = depolarizing

69
Q

TRP protein channels for TEMP

A

act as temp sensors
1. temps open gates of channel
2. allow nonspecific influx, dominated by Ca and Na+ = depolarizing
3. results in receptor potential initiating AP in afferent neuron
4. AP travels labeled line to brain to be perceived
some TRPs can be opened by chem ligands
- explains why capsaicin chem is perceived as hot and menthol as cool

70
Q

pain and itch

A

nociceptors are free axon terminals of small diameter afferent neurons with little/no myelination
bind to ligand gated ion channels on nociceptor plasma membrane
- glutamate and substance P neuropeptide are NTs releases a synapse on ascending neurons

71
Q

pain and itch NTs

A

glutamate and substance P neuropeptide are synapsed by nociceptor endings on ascending neurons

72
Q

referred pain

A

incoming nociceptive afferents activate interneurons, where sensation of pain is experienced at site other than injured/diseased tissue
EX: heart attack

73
Q

referred pain EX

A

heart attack
experience paining chest and arms
exciting the somatic afferent fibers activate receptors

74
Q

hyperalgesia

A

changes in nociceptors or ion channels result in increased sensitivity to painful stimuli

75
Q

inhibiting pain

A
  1. analgesia - selective suppression of pain w/out effects on consciousness or other sensations
  2. stimulation produced analgesia inhibits pain pathways by electrical stimulation to CNS
  3. endogenous opioids
76
Q

stimulation produced analgesia

A

inhibits pain pathways by electrical stimulation to CNS
descending pathways from the brain inhibit transmission of info from nociceptors
some neurons in inhibitory pathway release endogenous opioids which inhibit propagation of input through higher order levels of pain system

77
Q

endogenous opioids mediates placebo

A

acupuncture and placebo

78
Q

acupuncture

A

activate afferent neurons leading to carinal cord/midbrain that release endogenous opioids and NTs for pain relief

79
Q

TENS transcutaneous electrical nerve stimulation

A

painful site itself/nerves leading from it are stimulated by electrodes placed on skin surface
stimulation of non pain, low threshold afferent fibers leads to inhibition of neurons in pain pathway

80
Q

itch

A

somatic sensation w/ pain signaling pathway
can be mechanically activated to chemically mediated (anti/histamine)

81
Q

neural pathway of somatosensory system

A
  1. enter CNS, afferent nerve fibers from somatic receptors synapse on neurons of ascending pathways to somatosensory cortex via brainstem and thalamus
  2. synaps eon interneurons
82
Q

2 somatosensory pathways

A
  1. anterolateral pathway - spinothalamic
  2. dorsal column pathway
83
Q

anterolateral pathway

A

of somatosensory pathway
spinothalamic
1. 1st synapse ~ neurons in gray matter of spinal cord
2. 2nd neuron crosses to OPPOSITE side and ascents to thalamus
processes PAIN AND TEMP.

84
Q

Which pathway processes pain?

A

somatosensory - anterolateral

85
Q

Which pathway processes temp?

A

somatosensory - anterolateral

86
Q

dorsal column pathway

A

of somatosensory process
1. section of white matter the sensory receptor neurons project
2. neurons do NOT immediately cross or synapse
they ascend the same side and make 1st synapse in brainstem
secondary neuron crosses in brainstem and ascends
2nd synapse is thalamus, projections sent to somatosensory cortex

87
Q

compare anterolateral and dorsal column pathway

A

BOTH: somatosensory, 2nd synapse is thalamus
both cross at diff times
DIFF: dorsal - ascend on the same side of the cord and make the first synapse in the brainstem
anterolateral - makes its first synapse in the gray matter of spinal cord. This second neuron immediately crosses to the opposite side and ascends to thalamus

88
Q

somatosensory cortex end off pathway

A

endings of axons of specific somatic pathways are grouped by peripheral location of receptors that gave input
areas of body that are most densely innervated have largest area of somatosensory cortex
- overlap
- sizes change with sensory experience

89
Q

dynamic nature of somatosensory cortex

A

sizes change with sensory experience
ex: phantom limb - reorganization. cortical areas formerly responsible for a missing limb are “rewired” to respond to sensory inputs originating in the face

90
Q

afferent neurons

A

neurons carry information from sensory receptors towards CNS

91
Q

visible light

A

400-750nm

92
Q

the eye overview

A

3 layers, fluid filled, 2 chambers
1. sclera outer layer, white and tough connective tissue, muscles connect
also forms cornea - clear and dense
2. choroid under sclera - colored and absorbs light at back of the eye (uvea)
choroid contains iris (regulates pupil), ciliary muscle, zonular fibers = suspensory ligament
3. retina

93
Q

sclera

A

outer layer of eye
tough, fibrous white connective tissue that muscles attach to
forms clear dense cornea

94
Q

cornea

A

part of white sclera, dense and clear
covers iris and allows light to enter
can help focus image on retina

95
Q

choroid

A

middle layer of eye under sclera
absorbs light at back of the eye
mainly blood vessels
iris, ciliary muscle, zonular fibers = suspensory ligament

96
Q

iris

A

part of choroid layer
colored
regulates pupil diameter
2 layers of smooth muscle innervated by autonomic nerves
dilate: stim sympathetic nerves, cause radial muscle fibers to contract
constrict: stim parasympathetic fibers
integrate din midbrain

97
Q

pupil

A

regulated by iris smooth muscles
anterior opening allows light in

98
Q

lens

A

behind the iris
crytalline
controlled by activity go ciliary muscle and tension of zonular fibers that determine shape and focusing power
cells of lens lack ability to replicate except at surface
with age, central part of lens becomes denser/stiff with cells

99
Q

retina

A

formed as part of brain in embryo
forms inner posterior surface of eye
contains neurons and photoreceptors
macula lutea - yellow spot , relatively free of blood vessels; processes image
fovea centralis - in macula, high density of cones = high visual acuity
optic disc = nasal side of retina, neurons carry info from photoreceptors exit the eye as optic nerve

100
Q

2 chambers of eye

A

support
aqueous humor - anterior chamber of eye between iris and cornea
vitreous - posterior chamber of eye between lens and retina; viscous

101
Q

refraction

A

bending light to focus image on retina
lens refracts light inward, converges back into a point on retina
retina better at focusing light

102
Q

adjustments in lens shape

A

accommodation
controlled by ciliary muscle and tension it applies to zonular fibers which Utah to ciliary muscles to lens

103
Q

accommodation

A

adjustments in lens shape

104
Q

kinesthesia

A

sense of movement of a joint

105
Q

receptors for posture and movement

A

mechanoreceptors in skin, muscle, etc
- muscle-spindle stretch receptors
- golgi tendon organs (musc tension)
- vision and vestibular organs

106
Q

thermoreceptors

A

transmit temp info
skinny NON-myelinated afferent neurons are FREE NEURONS ENDINGS (no capsular ending)
temp sensor is ion channel in plasma membrane belonging to transient receptor potential proteins TRP proteins

107
Q
A